The present invention relates to a device and method for selectively clamping portable drills to work pieces; more particularly, the device of the present invention pertains to a device and method for clamping a portable drill to a work piece wherein holes are drilled in the work piece by reference to a pilot hole using a hole locating template.
Because of the increasing use of exotic and composite materials in many industrial applications, the task of accurately positioning portable hole drills with respect to a work piece without marring the surface of the work piece has become increasingly important and more difficult. One of the more common methods for positioning a portable drill with respect to a work piece begins with accurately positioning a pilot hole in the work piece. The remaining holes are formed by positioning the portable drill with respect to the accurately positioned pilot hole. In devices employing this method of hole location, a fixture for a portable drill is mounted on the work piece starting at the pilot hole. The pattern for the remainder of the holes to be drilled is laid out by use of a template. Once the drill clamping device and template have been located with respect to the pilot hole, the portable drill is positioned by reference to the template.
One of the drawbacks of this prior art portable drill locating system is the excessive force that has been required of the drill clamping fixture to hold the portable drill assembly in proper position for the drilling of the finish holes located by the template. These excessive forces are required because the unit can be back-driven. Such excessive clamping forces may mar the surface of the work piece or may actually deform the hole so that the work piece becomes unusable.
There is, therefore, a need in the art for a device which will position a portable drill for drilling finish holes in work pieces yet will exert only a minimum amount of force on a work piece. In the language of the trade, such devices are known as "soft foot" drill clamping attachments.